Variable throw eccentric mechanism



Jan. 2, 1951 MR. PLOTTS 2,536,213

VARIABLE THROW ECCENTRIC MECHANISM Filed March 28, 1949 5 Sheets-Sheet l Jan. 2, 1951 R. PLOTTS 2,536,213

VARIABLE THROW ECCENTRIC MECHANISM Filed March 28, 1949 '5 Sheets-Sheet 2 FIG. 3.

Jan. 2, 1951 V R. PLOTTS 2,536,213

VARIABLE THROW ECCENTRIC MECHANISM Filed March 28, 1949 5 Sheets-Sheet 5 Jan. 2, 1951 R. PLOTTS 2,536,213

VARIABLE THROW ECCENTRIC MECHANISM Filed March 28, 1949 5 Sheets-Sheet 4 FIG. 7.

Jan. 2, 1951 R. PLOTTS 2,536,213

VARIABLE THROW ECCENTRIC MECHANISM Filed March 28, 1949 5 Sheets-Sheet 5 FIG. 9.

Patented Jan. 2, 1951 OFFICE VARIABLE THROW ECCENTRIC MECHANISM Roland Plotts, McLeansboro, Ill.

Application March 28, 1949, Serial No. 83,923

11 Claims.

This invention pertains to pumping equipment, more particularly such as is used in pumping oil wells and the like, though it may be used with other similar equipment to which it is applicable.

In the pumping of an oil well. the rate of pumping must usually be adjusted to the rate of flow of the well. This rate of flow is not constant, but usually falls off as the pumping proceeds, becoming less and less until the well is practically dry. The rate of pumping must be adjusted accordingly and this is ordinarily done .by changing the stroke of the reciprocating pump which is the usual equipment.

One of the objects of this invention is to provide a pumper mechanism in which the stroke of the pump may be varied at will.

Another object is to provide such a mechanism in which such adjustment may be made in a simple and easy manner while t e pumper is running.

Another object is to provide an improved mechanical construction for such a mechan sm which will be inexpensive to build and easy to operate.

Further objects will appear from the following description, in which will be set forth an illustrative embodiment of this invention. It i understood, however, that this invention is susceptible of various embodiments, within the scope of the appended claims, without departing from the spirit or principles of the invention.

In accordance with this invention, generally stated, an improved driving mechanism is provided for the walking-beam of the usual pumping mechanism. The driving mechanism includes a pair of eccentrics cooperatively related to form a crank which latter is connected to rock the beam. Simple mechanism is provided for varying the relative positions of said eccentrics in order to vary the throw of said crank and thereby vary the stroke of the pump. This adjustment may be made while the mechanism is running, so the pumper need not be stopped for that purpose. I

An illustration embodiment of this invention is shown in the accompanying drawings, in which Figure 1 is a side elevation of a pumper embodying this invention;

Figure 2 is a view in elevation from the right side of Figure 1;

Figure 3 is an enlarged plan view of the driving mechanism with the cover removed and parts in section;

Figure 4 is a section on the line 4-4 of Figure Figure 5 is a section on the line 5-5 of Figure 3;

Figure 6 i a view similar to Figure 5, with the Figure 9 is a section on the line 9--9 of Fig-.

ure 3;

Figure 10 is an enlarged detail section onthe line Ill-Ill of Figure 3;

Figure 11 is a detail section on the line |lll of Figure 9.

Referring now to the drawings, I designates a supporting frame of any suitable design, which may include a housing for the mechanism and which, in the embodiment illustrated, also func tions as a conventional Samson post. journaled on the frame I are a drive shaft 2, a countershaft 3 and a load shaft 4. The drive shaft 2 may be driven by a prime mover in any suitable manner, as by a belt drive 5 from a motor 6 bracketed upon the frame. The drive shaft 2 carries a pinion 1 meshing with a gear 8 on the shaft 3. Rigidly connected to the gear 8 is another pinion 9, also on the shaft 3, and meshing with a gear l0 keyed to the shaft 4. Thus the shaft 4 is driven continuously at a reduced speed.

The gear Ill has formed thereon or secured thereto, as shown in Figure 10, an eccentric I I which rotates with the shaft 4 since the gear I0 is fixed to that shaft. Mounted to turn on the eccentric H is a second, outer eccentric l2 which, in turn, has formed or mounted thereon an internal gear I3. A conventional walking beam 4| is pivoted at l4 on the frame or support I and has rigidly secured thereto, at said pivot, a yoke bracket I5 having a pair of rigid arms 16 extending downward therefrom. The arms I6 are spaced apart just enough to space the outer diameter of the eccentric l2 with sufficient clearance to permit said eccentric to rotate between said arms. eccentric movement will cause the bracket l5, and with it the beam 4|, to rock on the pivot l4.

The rotation of the shaft 4 is counter-clockwise as seen in Figure 6. This causes the eccentric l2. to engage the right arm l6 at points below theshaft 4 during the up-stroke of the pump rod 43, and to engage the left arm l6 at points above the" shaft 4 during the down-stroke of the pump rod. Thus the eccentric l2 operates at a greater leverage with respect to the pivot l4 during the upstroke than during the down-stroke of said rod. Accordingly, the up-stroke will be slower than the down-stroke. This is advantageous since the rel- Suitably As such rotation takes place, they atively slow upward movement while lifting the heavy liquid column somewhat reduces the power required, while the rapid downward movement insures proper operation of the pump valve as the plunger moves down through the liquid col- It will be seen that the two eccentrics H and I2 form together a crank adapted to oscillate the beam 4|. The throw of this crank may be varied by rotating the two eccentrics relatively to each other. The minimum throw will be had with these eccentrics in the relative positions shown in Figures 5 and 6 in which these eccentrics are directly opposed to each other. The maximum throw may be had by turning one of those cams through 180 degrees relatively to the other. At intermediate positions the throw will vary gradually from minimum to maximum.

In order to vary the relative position of the two eccentric cams H and I2, the mechanism shown in section in Figure 10 is provided. A hub ll, carrying a brake drum is, is fixed on a sleeve ll, loose on the shaft 4, which sleeve has formed thereon or secured thereto a pinion 19 arranged to mesh with the internal gear [3 on theeam l2. The sleeve 11, is mounted in a suitable bearing 46 on the frame or support l. The outer cylindrical surface of the. hub ll forms a bearing for a clutch comprising a clamping member 20 the openends of which are connected by an adjustable link 21 operable by an eccentric cam 22 to clamp said member upon the hub H. The cam 22 is operable by a lever .23. one end of which is braced by a spring 24 (Fi ure .8) to free the cl mp and he other en o which is orm d with a finger 21 The latter fin er is po it oned. n the p th f a cone member .28 slidahle alo g the shaft 4 to engag nd lift said fin er to enga or ig the clutch. A do 2], extending be ween s 28 n he cl ping membe 213, has a collar 29 fixed to the shaft 4. Thus by sliding the member to the left, Figure 1!), the finger 25 is lifted to rotate the cam 22 and engage or tighten the clutch. When the member 28 is slid to the right, the finger 25 is released and the spring 2.4 releases the clutch. A lever 36 (see Figures 8 and 9), pivoted at 3! on the frame or support carries a brake shoe 32 en ageable with the drum 18 to stop its rotation.

Thus when the lever 23 is free and the clutch 233 free on the hub 11, said hub and with it th sleeve I1 and the pinion H}, are thereby free om the d 1 which. eaves th sh 4 t e to rotate independently. During such rotation the gea s 9 and i3 p rate to drive the eccentr c I2 in unison therewith, and this maintains a fixed relation between the eccentrics I I and I2. However, by moving the member 26 to drop the finger 25,, the clutch 2,! may he released. By now operatin the brake .shoe, 32 to stop the drum IB, the rotation of the pinion i9, is stopped. But the gear 13 maintains a controlling connection between the pinion l9 and the eccentric I2, and the latter eccentric stops rotating with the shaft 4, while the eccentric l I continues to rotate therewith. This causes a shift in the relative angulat-posit on an t ow of the eccentrics H and .1

ilfhe membe 6 carries a coll r .33 pivoted, at 3 3. to a han lever 35 (F u e which, turn, is pivoted at .35 .on the frame or support The hand lever 35 is connected by an adjustable link 31 (Figures 9 and 11 to a bellcrank 3,8 pivoted at 39, on the frame and having atits other end a perforation eye or socket All adapted to receive the end of the brake lever .30.. These connections are such that by movin the hand lever 35 to the right, Figure 3, the member 26 is shifted to drop the finger 25 to release the clutch 23. At the same time, or by further movement of the hand lever, the bellcrank 38 is operated to apply the brake shoe 32, to slow down or stop the drum l8 and the eccentric I2. Thus by manipulating the hand lever 35 while the countershaft 4 is running, the relative positions of the eccentrics II and I2 may be shifted and thereby the throw of the crank formed by the cooperative relation of said eccentrics, may be varied as above stated. By suitable adjustment of the link 3?, the actions of the clutch 20 and the brake shoe 32 can be so coordinated that any desired variation in the throw of the crank may be accomplished by momentarily slipping the clutch 2E] and the drum Hi.

In connecting this driving mechanism to the Well. pump n t shown.) the b a M may be vided with he usual beam ha g r 2 on Which the polish rod 43 is hung by a flexible wire line 4%,. fiuitable counterweights 55 may be mounted on the other end of the beam.

It will be seen, therefore, that this invention provides a simple mechanism for adjusting the pumping rate of a pumper of this kind. With a suitable adjustment. of the link 31, the relation of the clutch 2t and the brake 32 may be made such that a given movement of the lever 35 will permit both clutch and brake to slip sufiiciently to permit a slow shift of the eccentrics relatively to each other, so that the operator can gage the amount of such change and re-engage the clutch when the desired adjustment of the stroke has been obtained. Thus the throw or stroke of the crank can be varied gradually from minimum to maximum as desired. As the adjustment can be made while the pumper is running, no delay due to shut-downs is involved. Furthermore, repeated adjustments can be made, without losing time, and the exact stroke required can be readily obtained. Should the pump valves in the well become clogged or stuck by sediment, they can be quickly cleared and freed by merely lengthening the stroke enough, so as to bump the workin valves together for a few times,

It is thought that the construction, use and operation of the invention will be fully understood from the foregoing description, and while I have here shown and described a preferred embodiment of the invention, and specific structural features thereof, it is understood that the embodimerit shown and the several structural features thereof may be changed or modified as desired, within the scope however of the appended claims.

I claim:

1. In a pumper unit of the kind described, and" including a walking beam, said beam comprising a pair of relatively movable eccentrics co-operatively providing a crank, connections between said crank and said beam adapted to rock the latter under the movement of the crank provided by the eccentrics, a clutch and cooperating brake mQGhanism engageable to fix the relative positions of said eccentrics, and means operable to sl p sa d. c utch. for shi ing th r ative p it oningof the eccentrics for varying the throw of the rank as pro ided hereby- 'l n a pumper unit of' the kind described, and including a walking beam, driving means for said beam, comprising a shaft, a pair of rela tively movable eccentrics on said shaft and cooperatively related to. form and provide a variable throw crank, driving connections between said crank and said beam for rocking the latter under rotation of the eccentrics, a member loose on said shaft providing a connection between said eccentrics for shifting the same relatively, a clutch operable to lock said member to fix the relative positions of said eccentrics, braking means associated with said member, manipulating means connected to said clutch and said braking means for operating the same in timed relation to each other, and means for adjusting the timing of such operation.

3. In a pumper unit of the character described and for driving a walking beam, a rotatable shaft, inner and outer cooperating eccentrics mounted on the shaft and relatively angularly adjustable to form a variable throw crank, the inner eccentric being fixed on the shaft, a cooperating gear pair for adjusting the outer eccentric and varying the crank throw, a clutch for locking said gears, and a brake mechanism for retarding one of said gears of the pair as the clutch is released and thereby shifting the outer eccentric angularly with respect to the inner and varying the effective crank throw.

4. Adjustable drive mechanism of the character described for the walking beam of a pumper, comprising in combination, a rotary shaft, inner and outer eccentrics on the shaft and means operated by the outer eccentric for rocking said walking beam, the inner eccentric being fixed on the shaft and the outer eccentric angularly adjustable with respect to the inner to operate as a variable throw crank, a gear on the outer eccentric, a brake member, a gear on said brake member meshing with the first mentioned gear, a clutch normally locking the brake member to the shaft to rotate therewith, and means operative to retard the brake member and gear thereon as the clutch is released to thereby adjust the outer eccentric on the inner.

5. Adjustable drive mechanism of the character described for the walking beam of a pumper, comprising in combination, a rotary shaft, inner and outer eccentrics on the shaft and means operated by the outer eccentric for rocking said walking beam, the inner eccentric being fixed on the shaft and the outer eccentric being angularly adjustable around the inner eccentric to operate as a variable throw crank, means including a manually releasable clutch normally locking the outer eccentric to rotate with the shaft, and means operative when said clutch is released for holding the outer eccentric as the inner rotates and thereby varying the angular relationship between the eccentrics.

6. Adjustable drive mechanism of the character described for the walking beam of a pumper, comprising in combination, a rotary shaft, inner and outer eccentrics on the shaft and means operated by the outer eccentric for rocking said walking beam, the inner eccentric being fixed on the shaft and the outer eccentric being adjustable with respect to the inner to operate as a variable throw crank, a gear on the outer eccentric, a brake member, a gear on said brake member meshing with the first mentioned gear, a clutch normally locking the brake member to the shaft to rotate therewith, and means operative to retard the brake member and gear as the clutch is released to thereby adjust the outer eccentric on the inner, the said brake member and clutch being mounted about the axis of the shaft.

'7. Adjustable drive mechanism of the character described for the walking beam of a pumper, comprising in combination, a rotary shaft, inner and outer eccentrics on the shaft and means operated by the outer eccentric for rocking said walking beam, the inner eccentric being fixed on the shaft and the outer eccentric adjustable with respect to the inner to operate as a variable throw crank, a gear attached to the outer eccentric, a hub journaled on the shaft and having a gear meshing with the first mentioned gear, a clutch for locking the hub to the shaft to rotate therewith while maintaining the gears and eccentrics in adjusted positions, means for releasing the clutch, and a brake for retarding the hub as the shaft continues to rotate whereby the gears will angularly adjust the outer eccentric on the inner and vary the throw of the crank.

8. Adjustable drive mechanism of the character described for the walking beam of a pumper, comprising in combination, a rotary shaft, inner and outer eccentrics 0n the shaft and means operated by the outer eccentric for rocking said walking beam, the inner eccentric being fixed on the shaft and the outer eccentric being angularly adjustable with respect to the inner to operate as a variable throw crank, a gear attached to the outer eccentric, a hub journaled on the shaft and having a gear meshing with the first mentioned gear, a clutch for locking the hub to the shaft to rotate therewith while maintaining the gears and eccentrics in adjusted positions, means for releasing the clutch, a brake drum on said hub, and a brake shoe applicable to said drum to retard the hub and gear as the clutch is released to thereby adjust the outer eccentric with respect to the inner as the latter continues to rotate.

9. Adjustable drive mechanism of the character described for the walking beam of a pumper, comprising in combination, a rotary shaft, inner and outer eccentrics on the shaft and means operated by the outer eccentric for rocking said walking beam, the inner eccentric being fixed on the shaft and the outer eccentric angularly adjustable on the inner to operate as a variable throw crank, a gear on the outer eccentric, a hub journaled on the shaft and having a gear meshing with the gear on said outer eccentric, a clutch for locking the hub to the shaft to rotate therewith while maintaining the gears and eccentrics in adjusted position, a cone member movable on the shaft, means operated by movement of said cone member for releasing the clutch, a brake operative to retard the movement of the outer eccentric as the clutch is disengaged whereby the continued rotation of the inner eccentric will adjust the effective crank throw, and manually operative means for operating the cone member and brake.

10. Adjustable drive mechanism of the character described for the walking beam of a pumper, comprising in combination, a rotary shaft, inner and outer eccentrics on the shaft and means operated by the outer eccentric for rocking said walking beam, the inner eccentric being fixed on the shaft and the outer eccentric adjustable with respect to the inner to operate as a variable throw crank, a, gear on the outer eccentric, a hub journaled on the shaft and having a gear meshing with the gear on said outer eccentric, a clutch for locking the hub to the shaft to rotate therewith while maintaining the gears and eccentrics in adjusted position, a cone member movable on the shaft, means operated by movement of said cone member for releasing the clutch, a brake operative to retard the movement of the outer eccentric as the clutch is disengaged whereby the continued rotation of the inner eccentric will adjust the effective crank throw, and manually operative means for operating the cone member and brake in sequence and. including a, single hand lever.

11. In a pumper unit of the character described and for driving a walking beam, a rotatable shaft, inner and outer cooperating eccentrics mounted on the shaft and relatively angularly adjustable to form a variable throw crank, the inner eccen tric being fixed on the shaft, a cooperating gear pair for adjusting the outer eccentric and varying the crank throw, a clutch for locking said gears, a brake mechanism for retarding one of said gears of the pair as the clutch is released and thereby shifting the outer eccentric angularly With respect to the inner and varying the crank throw, means for operating the clutch and means for operating the brake mechanism, a single hand lever for operating one of said means, and an adjustable link connecting the lever to the other of said means for adjusting the timing between the operation of the clutch and the brake mechanism as the hand lever is adjusted.

ROLAND PLOTTS.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,091,035 Bohm et a1 Mar. 24, 1914 1,732,475 Kenyon Oct. 22, 1929 1,907,647 Gruman May 9, 1933 2,169,493 Humphrey Aug. 15, 1935 

